1. Field of the Invention
The invention relates to a battery module.
2. Description of the Related Art
In recent years, various secondary batteries have been proposed as the power sources for portable devices and mobile devices and also as the power sources for electric vehicles and hybrid vehicles (For example, see JP-A-2001-93505).
The secondary battery (battery module) described in JP-A-2001-93505 has: electrode assemblies each including a positive electrode plate, a negative electrode plate, and two current collector plates (the first and second current collector plates) for the positive electrode and the negative electrode, respectively; and a case having a plurality of battery chambers (mounting spaces) partitioned from each other by partitioned walls. In the electrode assembly, the first current collector plate is welded to one of the positive electrode plate and the negative electrode plate and the second current collector plate is welded to the other of the positive electrode plate and the negative electrode plate, and each electrode assembly is disposed in a corresponding one of the battery chambers, whereby a battery cell is formed therein. In each battery cell, the connecting post (connecting portion) of each power current collector plate (the first current collector plate) is connected to the connecting post (connecting portion) of the other power current collector plate (the second current collector plate) of the adjacent battery cell, via a communication hole (connecting hole) formed in the partition wall of the case, whereby the battery module is formed.
In some of such secondary batteries, the current collector plates of each electrode assembly (power generation element), which are located adjacent to each other and disposed in the respective battery chambers, are bended so as to allow their connecting posts (connecting portion, adjacent connecting portion) to be connected to each other in a communication hole (connecting hole) in the partition wall in the case, and the connecting posts are attached to each other by welding, or the like. With this arrangement, an elastic force acting in the direction in which the connecting posts of the adjacent current collector plates are detached away from each other may remain in some of the current collector plates. In this case, pressure may concentrate on the welded point between the current collector plate with the remaining elastic force and the electrode plate that is located closest to the connecting portion and on the vicinity of that welded point, so that the welded point is ruptured and the electric resistance between the current collector plate and the electrode plate thus increases at the ruptured point.